Question : reverse ajax

How to implement a gmail like "change caption" ?
What i want is ,if i do any change in gmail,the change is reflected to another user without refreshing the browser

what is the technology behind this?

Please help me in finding a solution.

Thanks in advance

Answer : reverse ajax

MobileMe?  That's the only thing I know of that can solve this one currently.  I use Google MS exchange sync for everything else, but I don't see how you can use an iPhone without iTunes.  Apple has this one locked in, Sherman legal or not, you don't have much choice here right now....